High-temperature erosion of HVOF sprayed Cr₃C₂ -NiCr coating and mild steel for boiler tubes

The comparison of the high-temperature erosion behavior of a High-velocity oxyfuel (HVOF) sprayed Cr₃C₂-NiCr coating with mild steel for circulating fluidized bed boiler tubes was investigated. Results showed that the erosion rate of the mild steel at 800 °C was four times that at 300 °C at an erosion angle of 30°. However, the erosion rate of the HVOF sprayed Cr₃ C₂-NiCr coating was not influenced by the temperature in the range of 300-800 °C. It was found that the erosion resistance of HVOF sprayed Cr₃C₂-NiCr coating was more than three times higher than that of the mild steel at 700-800 °C. In addition to the ploughing on the coating surface, the cracking along splat interfaces in the coating was clearly observed on the cross-sectional microstructure. The results indicate that the erosion performance of the HVOF sprayed Cr₃C₂-NiCr coating is controlled by the cohesion between splats and can be further enhanced by improving splat cohesion.